SEX DIFFERENCES IN THE LINK BETWEEN DNA METHYLATION–BASED BIOLOGICAL AGING AND HEALTH IN OLDER INDIVIDUALS

Abstract It is well-established that women live longer than men, however, sex differences in biological aging have not been consistently reported, and may differ depending on the measure used. This study aimed to determine the correlation between DNA methylation (DNAm) age acceleration (AA) measures, with system-wide frailty-index (FI) aging and brain-predicted age difference (brain-PAD), in an initially healthy population of men and women aged ≥70 years. We additionally explored the extent to which these AA measures were associated with clinical measures, and chronic conditions, separately in men and women. DNAm age (Horvath, Hannum, PhenoAge, GrimAge, and DunedinPACE) were estimated in blood from 560 Australians (women, 50.7%) enrolled in the ASPREE study. FI was a deficit accumulation of 67 items including cognition and morbidities. Brain age was estimated from T1-weighted MRI. Clinical measurements, laboratory tests, and self-reports were used to identify chronic illnesses. FI had the strongest correlation with GrimAA and DunedinPACE (range r: 0.20 to 0.24 in both sexes) but was not associated with HorvathAA. Brain-PAD was not correlated with any biological aging measure. Correlations between AA and clinical measures were more commonly found in women than men and were the strongest for DunedinPACE and clinical measures including grip strength, gait speed, and self-rated health (r: -0.23 to 0.24). AA measures, especially GrimAA and DunedinPACE, were significantly associated with hypertension, diabetes, chronic kidney disease in men, and obesity and depression in women. Our findings highlight the importance of considering sex differences when investigating the link between biological age and clinical measures.


United States
The placenta exists in a hypoxic environment during early pregnancy, making it susceptible to somatic genetic mutations caused by oxidative stress and rapid cell proliferation.Oxidative stress is one of the leading factors involved in cellular aging causing genetic mutations, cellular senescence, and mitochondria dysfunction over time.While it has been demonstrated that healthy placentas accumulate somatic mutations as they develop, we hypothesize that diseased placentas display an accelerated aging phenotype through the accumulation of somatic mutations.To address this, we analyzed RNA-seq data from 84 human placentas throughout gestation from healthy (N=33) and preeclamptic pregnancies (N=51).We identified rare single nucleotide variants, insertions and deletions using GATK Best practices Workflow for RNA-seq short variant discovery using bcbionextgen and annotated with VEP and LOFTEE.Mutational burden, defined as the total number of rare mutations per megabase, was calculated after strict quality control and filtering for rare (gnomADg< 0.05) variants using maftools in R. Linear regression models were employed to determine the association between mutational burden and gestational age.Differences in mean values were computed with a pairwise t-test .This study revealed that mutational burden in earlyonset preeclampsia placentas is negatively correlated to gestational age (R^2=0.256;p-value=0.032).The early-onset preeclampsia group had a higher mutational burden relative to the other groups (p-value< 0.05).This study revealed a significant correlation of mutational burden with gestational age in early-onset preeclampsia, paving the way for additional investigation of accelerated aging in placentas and its contribution to the development of preeclampsia.

SEX DIFFERENCES IN THE LINK BETWEEN DNA METHYLATION-BASED BIOLOGICAL AGING AND HEALTH IN OLDER INDIVIDUALS
Aung Zaw Zaw Phyo 1 , Peter Fransquet 2 , Jo Wrigglesworth 3 , Robyn Woods 3 , Sara Espinoza 4 , and Joanne Ryan 3 , 1. Monash University,Melbourne,Australia. ,Melbourne,Victoria,Australia,2. Deakin University,Burwood East,Victoria,Australia,3. Monash University,Melbourne,Victoria,Australia,Los Angeles,California,United States It is well-established that women live longer than men, however, sex differences in biological aging have not been consistently reported, and may differ depending on the measure used.This study aimed to determine the correlation between DNA methylation (DNAm) age acceleration (AA) measures, with system-wide frailty-index (FI) aging and brain-predicted age difference (brain-PAD), in an initially healthy population of men and women aged ≥70 years.We additionally explored the extent to which these AA measures were associated with clinical measures, and chronic conditions, separately in men and women.DNAm age (Horvath, Hannum, PhenoAge, GrimAge, and DunedinPACE) were estimated in blood from 560 Australians (women, 50.7%) enrolled in the ASPREE study.FI was a deficit accumulation of 67 items including cognition and morbidities.Brain age was estimated from T1-weighted MRI.Clinical measurements, laboratory tests, and self-reports were used to identify chronic illnesses.FI had the strongest correlation with GrimAA and DunedinPACE (range r: 0.20 to 0.24 in both sexes) but was not associated with HorvathAA.Brain-PAD was not correlated with any biological aging measure.Correlations between AA and clinical measures were more commonly found in women than men and were the strongest for DunedinPACE and clinical measures including grip strength, gait speed, and self-rated health (r: -0.23 to 0.24).AA measures, especially GrimAA and DunedinPACE, were significantly associated with hypertension, diabetes, chronic kidney disease in men, and obesity and depression in women.Our findings highlight the importance of considering sex differences when investigating the link between biological age and clinical measures.

SEX STEROID HORMONES AND AGE AT DEATH-A MENDELIAN APPROACH
Cynthia Kusters, Kimberly Paul, and Beate Ritz, University of California, Los Angeles, Los Angeles, California, United States Lower concentrations of testosterone have been associated with increased mortality and shorter lifespan in observational studies.An association between androgens and decreased epigenetic age was identified among men.Here, we assessed the association between sex steroid hormones and parental age at death using a Mendelian randomization (MR) approach.An inverse-variance weighting (IVW) MR analysis was performed using effect estimates from external GWAS summary statistics.We included independent variants (linkage disequilibrium R2< 0.001) and a P-value threshold of 5x10-8.Sensitivity analysis included changing the P-value thresholds, MR method and multivariable MR analysis.An increase in androsterone sulfate and DHEAS were associated with a lower age at death for both fathers and mothers (-0.04/-0.05years, P-value: 7e-4/7e-4), as well as the combined parental age at death (-0.06 years, P-value:5e-4).In addition, an increase in SHBG was associated with a higher age at death (0.06 years, P-value:7e-5).We did not find an association with estradiol or testosterone and age at death.Sensitivity analysis showed consistent findings.Our study could suggest that a higher concentration of androgens, specifically androsterone sulfate and DHEAS, decrease lifespan.This is contradictory to observational studies and deserves further attention.However, the SNPs associated with these androgens are also strongly associated with body mass index (BMI).Adjusting for BMI in the MR models removes the association between sex hormones and age at death.We are currently performing more analyses to shed light on this association.

SIRTUIN 1 ISOFORMS DIFFERENTIALLY IMPACT MITOCHONDRIAL GENE EXPRESSION AND FUNCTION IN MUSCLE CELLS
Xiaomin Zhang, Pankaj Patyal, Ambika Verma, Shakshi Sharma, Gohar Azhar, Fathima Ameer, Yingni Che, and Jeanne Wei, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States Background Alternative splicing (AS) is a mechanism that generates multiple mRNA transcripts and protein isoforms from a single gene, thereby increasing transcriptomic and proteomic diversity.The spliced isoforms commonly lack one or more exons, which may have similar or even opposite functions.Alternatively spliced isoforms tend to increase during aging.The sirtuin-1 gene contains multiple exons and undergoes alternative splicing, which generates multiple isoforms.In this study, we assessed the impact of three sirtuin-1 isoforms on mitochondrial gene expression and function in muscle cells.Methods Three sirtuin-1 isoforms (V1, V2, V3) were subcloned into expression vectors.Muscle cell lines (H9C2 and C2C12) were transfected with sirtuin-1 isoforms, respectively.Microscopic images were obtained using a Nikon microscope.Gene expression was determined by quantitative RT-PCR and Western blotting.The mitochondrial function was determined with a Seahorse XFe96 Analyzer.Results and conclusions The sirtuin-1 V1 isoform significantly increased the oxygen consumption rate (OCR) and decreased glycolysis (ECAR) in muscle cells, while V2 and V3 isoforms had slight or no significant effect on OCR and ECAR.V1 isoform was localized in the nucleus, whereas V2 and V3 were localized in the cytoplasm.Sirtuin-1 isoforms differentially impacted mitochondrial complex genes, including NDUFS1, NDUFV1, NDUFV2, NDUFA5.Our data indicate that the domain loss changed sirtuin-1 isoform subcellular localization, differentially impacted mitochondrial gene expression, and affected mitochondrial function.The age-related change in the expression of sirtuin-1 isoforms could affect cardiac and skeletal muscle function in aging and senescence.Further exploration of the sirtuin-1 isoforms' functions is warranted.

TRANSCRIPTOMIC SIGNATURES FOR AGING AND EXTREME OLD AGE IDENTIFIED IN LONG LIFE FAMILY STUDY
Mengze Li 1 , Zeyuan Song 1 , Tanya Karagiannis 2 , Stefano Monti 1 , Paola Sebastiani 2 , Thomas Perls 1 , and Michael Brent 3 , 1. Boston University, Boston,Massachusetts,United States,2. Tufts Medical Center,Boston,Massachusetts,United States,3. Washington University in St. Louis,St. Louis,Missouri,United States Transcriptional studies of blood have previously identified changes in gene expression profiles associated with age.Centenarians, a rare population of individuals that reach 100 years of age, experience delays in aging-related diseases and mortality.Thus, the analysis of their blood transcriptome may help shed light on mechanisms contributing to healthy aging and extreme longevity, as well as enable the discovery of candidate molecular therapeutic targets.In this project, we analyzed RNAseq-based blood transcriptomic